1. Field of the Invention
This invention relates to an endoscope signal processing apparatus wherein both of a field sequential type imaging means and a synchronous type imaging means can be used.
2. Related Art Statement
Recently, there is extensively used an endoscope (called a scope or fiber scope) whereby an organ or the like within a body cavity can be observed by inserting an elongate insertable part into the body cavity and any curing treatment can be made by using, as required, a treating tool inserted through a treating tool channel.
Also, there are suggested various electronic scopes wherein a solid state imaging device such as a charge coupled device (CCD) is used for the imaging means. Compared with the fiber scope, the electronic scope has advantages such as the resolution is higher, it is easier to record and reproduce picture images and picture image treatments such as the enlargement of picture images and the comparison of two picture images are easier.
Among the color picture image imaging systems of the above mentioned electronic scope, there are a field sequential system, wherein the illuminating light is switched sequentially to R (red), G (green) and B (blue) as shown, for example, in the gazette of a Japanese patent laid open No. 82731/1986, and a synchronous system (also called a color mosaic system) wherein a filter array in which color filters transmitting respectively such color lights as of R, G, and B are arranged in the form of a mosaic is provided on the front surface of a solid state imaging device as shown, for example, in the gazette of a Japanese patent laid open No. 76888/1985. The field sequential system has an advantage that the size can be made smaller than in the synchronous system. On the other hand, the synchronous system has an advantage that no color is displaced.
There are many kinds of the above mentioned electronic scope depending on the object of use. For example, an electronic scope in which the outside diameter of the insertable part is about 10 mm is used for the upper or lower digestive organ. On the other hand, for example, an electronic scope in which the outside diameter of the insertable part is about 5 mm is necessary for the bronchus. It is physically and functionally unreasonable to use the same kind of imaging device and the same kind of imaging system for various electronic scopes in which the outside diameters of the insertable parts are over a wide range. For example, in order to realize an electronic scope for the bronchus (small diameter), an imaging device of a small number of pixels must be used.
When the number of pixels is small, in order to prevent the reduction of the resolution, the field sequential type color imaging system whereby an object is field sequentially illuminated with lights of respective wavelengths of R, G and B and is field-sequentially imaged under these illuminations and the images are combined and color-displayed is more advantageous than the synchronous type imaging system wherein a color mosaic filter is used.
On the other hand, for the outside diameter of about 10 mm of the insertable part, it is advantageous in improving the picture quality to increase the number of pixels and to synchronize the imaging system.
Now, the above mentioned fiber scope or electronic scope is used generally as connected to a light source apparatus feeding an illuminating light adapted to each scope and a video processor processing video signals.
In the above mentioned fiber scope, field sequential type electronic scope and synchronous type electronic scope, the illuminating method and signal process are different. The conventional video processor corresponds to either of the field sequential type and synchronous type. Therefore, the use has to prepare respectively different video processors and make different operations depending on the kinds of the scope. It is low in economy and efficiency.
In the field sequential type and synchronous type, signals are processed partly in the same manner. However, the video processor is entirely independent of both imaging systems and therefore can not be used partly in common. In case the video processors of both imaging systems are prepared, the cost will increase and the apparatus will become large.
In case the video processor is independent of the field sequential type and synchronous type, the output ends will be respectively different. Therefore, when of displaying on a color monitor, the color monitor must be connected to the output end corresponding to the imaging system of the electronic scope to be used so that the operation is complicated.
In the gazette of a Japanese patent laid open No. 243625/1985, there is disclosed a connecting system whereby a fiber scope provided with an optical fiber bundle for transmitting images is connected to a controlling apparatus of a field sequential type electronic scope so that the image may be observed on the displaying picture surface of a monitor television or the like. However, in this system, a scope provided with a synchronous type imaging means can not be used.
Now, in a signal processing apparatus of an electronic scope of the above mentioned field sequential type, the signals read out of the solid state imaging device for the respective illuminating lights are A/D converted, are stored in the respective frame memories of R, G and B and are synchronously read out of the frame memories to produce a picture image signal. Therefore, by utilizing the above mentioned frame memories, the picture image can be frozen to display a stationary picture.
However, conventionally, there have been problems that at the time of freezing, a real time moving picture can not be displayed and information during freezing can not be obtained.